When an elongated member for medical use such as a catheter, a guide wire, etc. is to be guided into a living body, an introducer is oftentimes used.
The introducer includes a cylindrical hub (joint part), a valve body (check valve) disposed in one end portion of the hub, and a tube connected to the other end portion of the hub. An example of a valve body used in the introducer in this manner is one made of a flexible elastic material such as silicone rubber, as described in Japanese Patent Publication No. Hei 2-949.
The valve body is formed with an opening/closing (opening and/or closing) port (e.g., slit or minute hole) which opens or closes as the elongated member is inserted or pulled out. In addition, for reducing the sliding resistance (frictional resistance) on the elongated member when the elongated member is inserted, the valve body should have lubricity on its surface, particularly at the opening/closing port. To meet this requirement, a lubricating liquid such as a silicone oil is applied to the vicinity of the opening/closing port so as to reduce the sliding resistance of the valve body on the elongated member.
When the insertion and pulling-out of the elongated member through the opening/closing port is repeated, however, the lubricating liquid applied in the vicinity of the opening/closing port gradually becomes leaner. Eventually, the lubricating liquid runs out, leading to an increase in the sliding resistance of the elongated member. In the introducer having such a valve body, therefore, the presence of the lubricating liquid influences the sliding properties of the elongated member. Accordingly, the introducer may suffer a problem in that the operability of the elongated member is reduced during use.
In addition, the introducer as a medical instrument may sometimes be subjected to a sterilizing treatment by irradiation with radiant rays. However, the flexible elastic material such as silicone rubber undergoes alteration or deterioration when exposed to radiant rays. The alteration or deterioration is due to the process in which molecular chains in the silicone rubber are cut by the radiant rays and oxygen in the atmospheric air is bonded to the cut ends of the molecular chains. In this manner, the properties of the silicone rubber are changed, whereby the valve body's function is damaged. For this reason, the conventional valve bodies have a problem that it is difficult to sufficiently sterilize them by use of radiations.